A framework for proof certificates in finite state exploration

Model checkers use automated state exploration in order to prove various properties such as reachability, non-reachability, and bisimulation over state transition systems. While model checkers have proved valuable for locating errors in computer models and specifications, they can also be used to prove properties that might be consumed by other computational logic systems, such as theorem provers. In such a situation, a prover must be able to trust that the model checker is correct. Instead of attempting to prove the correctness of a model checker, we ask that it outputs its "proof evidence" as a formally defined document--a proof certificate--and that this document is checked by a trusted proof checker. We describe a framework for defining and checking proof certificates for a range of model checking problems. The core of this framework is a (focused) proof system that is augmented with premises that involve "clerk and expert" predicates. This framework is designed so that soundness can be guaranteed independently of any concerns for the correctness of the clerk and expert specifications. To illustrate the flexibility of this framework, we define and formally check proof certificates for reachability and non-reachability in graphs, as well as bisimulation and non-bisimulation for labeled transition systems. Finally, we describe briefly a reference checker that we have implemented for this framework.Comment: In Proceedings PxTP 2015, arXiv:1507.0837

Minimal Proof Search for Modal Logic K Model Checking

Most modal logics such as S5, LTL, or ATL are extensions of Modal Logic K. While the model checking problems for LTL and to a lesser extent ATL have been very active research areas for the past decades, the model checking problem for the more basic Multi-agent Modal Logic K (MMLK) has important applications as a formal framework for perfect information multi-player games on its own. We present Minimal Proof Search (MPS), an effort number based algorithm solving the model checking problem for MMLK. We prove two important properties for MPS beyond its correctness. The (dis)proof exhibited by MPS is of minimal cost for a general definition of cost, and MPS is an optimal algorithm for finding (dis)proofs of minimal cost. Optimality means that any comparable algorithm either needs to explore a bigger or equal state space than MPS, or is not guaranteed to find a (dis)proof of minimal cost on every input. As such, our work relates to A* and AO* in heuristic search, to Proof Number Search and DFPN+ in two-player games, and to counterexample minimization in software model checking.Comment: Extended version of the JELIA 2012 paper with the same titl

The interaction of lean and building information modeling in construction

Lean construction and Building Information Modeling are quite different initiatives, but both are having profound impacts on the construction industry. A rigorous analysis of the myriad specific interactions between them indicates that a synergy exists which, if properly understood in theoretical terms, can be exploited to improve construction processes beyond the degree to which it might be improved by application of either of these paradigms independently. Using a matrix that juxtaposes BIM functionalities with prescriptive lean construction principles, fifty-six interactions have been identified, all but four of which represent constructive interaction. Although evidence for the majority of these has been found, the matrix is not considered complete, but rather a framework for research to explore the degree of validity of the interactions. Construction executives, managers, designers and developers of IT systems for construction can also benefit from the framework as an aid to recognizing the potential synergies when planning their lean and BIM adoption strategies

The mediating roles of disgust sensitivity and danger expectancy in relation to hand washing behaviour

Copyright © 2010 British Association for Behavioural and Cognitive PsychotherapiesBackground: Recent interest in the role of vulnerability factors in obsessional washing has suggested that disgust sensitivity, danger expectancy and health anxiety may be of interest. Aims: This study explores the differential impact of these factors on both behavioural and cognitive measures of washing behaviour and is based on a replication of the Jones and Menzies (1997) experiment, during which participants immersed their hands in a noxious compound while rating themselves on a range of measures: the time they subsequently took to wash their hands was measured and danger expectancies were found to be the best predictor of this. Method: The present study added measures of disgust sensitivity and health anxiety to this experimental methodology while removing factors they found to be of little import to compulsive washing. Thirty non-clinical participants took part. Results: Results confirmed that disgust sensitivity was related to the behavioural measure of washing time, but that this relationship was almost entirely mediated by the danger expectancy concerning judgements of severity of consequent disease. However, a different pattern emerged when the outcome measure was questionnaire based: danger expectancy was not at all related to this. Disgust sensitivity mediated the relationship between health anxiety and scores on a questionnaire measure of washing compulsions. Interestingly, these scores were not related to the behavioural measure of washing time. Conclusions: The implications of these relationships to the further development of subtypes of Obsessive Compulsive Disorder (OCD) are discussed

The Search for Invariance: Repeated Positive Testing Serves the Goals of Causal Learning

Positive testing is characteristic of exploratory behavior, yet it seems to be at odds with the aim of information seeking. After all, repeated demonstrations of one’s current hypothesis often produce the same evidence and fail to distinguish it from potential alternatives. Research on the development of scientific reasoning and adult rule learning have both documented and attempted to explain this behavior. The current chapter reviews this prior work and introduces a novel theoretical account—the Search for Invariance (SI) hypothesis—which suggests that producing multiple positive examples serves the goals of causal learning. This hypothesis draws on the interventionist framework of causal reasoning, which suggests that causal learners are concerned with the invariance of candidate hypotheses. In a probabilistic and interdependent causal world, our primary goal is to determine whether, and in what contexts, our causal hypotheses provide accurate foundations for inference and intervention—not to disconfirm their alternatives. By recognizing the central role of invariance in causal learning, the phenomenon of positive testing may be reinterpreted as a rational information-seeking strategy

Navigating Independent Double Checks for Safer Care: A Nursing Perspective

Abstract The purpose of this study was to explore registered nurses’ understanding and practice of “independent double-checks” prior to administration of high-alert medications. The study used a qualitative descriptive design for data collection and data analysis. It included thirteen participants from a hospital located in southern New Hampshire. Results of the study revealed a core theme of navigating independent double checks (IDC) for safer care. Two major themes stemming from the core theme were also uncovered. Navigating IDC through knowing and navigating IDC through nurse partnership both focused on the perception and practice on IDC prior to administration of high alert medications. IDC was accepted and promoted as best practice, but the definition and process is still unclear. Having a universal definition will assist in clarity of the process and in turn, promote ensuring safe administration of high alert medications to patients. Keywords: independent double check, safer care, knowing, nurse partnershi